I'm struggling to find a comparison but I think it's probably because there's a clear and easy migration path that they can shut it off for users who pay the company, and expect support, and not that it was free and in beta. I don't mean legally acceptable because it's spelled out in the ToS, but acceptable to the community.
Yeah that's why it seems bad now. But hopefully for them they thought it through and most wanted to upgrade right away anyway the data regeneration will be quick.
AWS is an example. There are plenty of services which have a free tier. If you are depending on that service you would hope that Amazon doesn't just delete it from out under you. Unlike a pricing update. You can't just pay more to prevent production going down.